Almost half of Bradford Council schools still contain potentially-deadly asbestos, new figures reveal.

And a teaching union fears that with more schools moving out of local authority control to become academies, efforts to prevent staff and pupils from possible harm could be diluted.

The Council has stressed that it keeps a close watch on the management of asbestos in its school buildings but the National Union of Teachers has warned that when schools become academies, there is a risk of losing track of that vital information.

The UK Asbestos Training Association has also stressed that it is essential that both school staff and any builders carrying out work on them make sure they know where asbestos is located.

The association claims that 75 per cent of schools in the country still contain asbestos, although in Bradford that figure is lower, with 96 out of 205 Council schools still containing the material.

Asbestos is commonly found in ceiling tiles, heating systems and wall coverings and can become dangerous when it is damaged as potentially deadly fibres are then exposed.

A spokesman for UKATA said: “More than 140 teachers have died from mesothelioma (a cancer caused by asbestos exposure) in the last ten years, plus an unknown number of cleaners, dinner ladies and in some cases workers who have unwittingly taken on the job of removal without adequate training.

“Teachers need to think twice before fixing work to walls in such a way that would disturb asbestos and builders need to ensure they have the training and skills necessary to remove and dispose of the material safely.”

Ian Murch, Bradford national executive member for the National Union of Teachers, said: “Teachers in Bradford have died of mesothelioma, and families have been compensated on the basis that the exposure happened in the schools they worked in.

“It is not just an issue for teachers, it is an issue for pupils, because they are far more vulnerable when they are young.

“As with anything these days, there is the issue of having the money to remove it, but it needs to be managed. It can just mean keeping good records of where it is and making sure you don’t disturb it.

“With the number of academies that are no longer under council control, it is going to be harder to keep track of where asbestos is.

“Teachers, staff and pupils need to know where asbestos is – it is absolutely vital a record is kept.”

Councillor Ralph Berry, the executive member for education on Bradford Council, said that many schools containing asbestos had been closed or replaced, and that others were being closely monitored.

He said: “It can be kept safe if it is properly dealt with if we keep a close watch on it. It is a responsibility we as a Council take very carefully.”

On the NUT’s fear that academy schools are out of Council control, he added: “That is a very good point. That is one of the problems when you fragment the system, it makes it harder to maintain levels of security. I can understand the point the union is making and I agree with it.”

In recent years two former teachers in Bradford have died due to their exposure to asbestos while teaching.

Graham Butterfield, who taught at the former Hutton Middle and Tong schools between 1967 and 1996, died aged 64 in early 2011, and an inquest into his death found that exposure to the fibres had led to him developing mesothelioma.

Following the inquest his widow, Marilyn, of Idle, Bradford, said: “I cannot believe that he was exposed to this dust in a teaching environment which should be a safe place for our children to learn.”

Graham Webber, of Heaton, Bradford, a former teacher at Daisy Hill Middle School, died aged 57 in 2010 and a subsequent inquest also ruled that his death was by industrial disease caused by asbestos.

l Tong School in Westgate Hill has since been demolished and rebuilt.